I wouldn’t think this is possible unless those lenses are designed for different sized media ie: the 16mm lens for medium format film and the 8mm lens for 35mm film. That’s just an not to well educated guess:-)
8mm and 16mm are just the focal length numbers. You can make a fisheye with 180 degree field of view with a 50mm lens! The shape of the front objective lens determines the image that is passed down the lens barrel.
thanks.
:)